Bought this PSU two or three years ago when it was listed at silentpcreview.com as the most silent PSU...

About a year back it has started to give me problems when I turn it on, just will not power on but after a few tries it does, feels to me like it needs to warm up first... Once it is on the voltage rails are within 3% and my PC very rarley gets a BSOD, but I have gotten one or so per month during this year and I think it's due to the PSU...

Well yesterday I took it apart, the problems lies with 4 bulging Fuhjyyu TNR 105°C caps 2x 3300uF 10v and 2x 1000Uf 10v

I've already bought Sanyo MV-WX replacement caps (not same physical size though) will report back when I have swapped those caps...

uh oh.. those fuhjyyu are evil.. im a fan of silent system too.. have been of a spcr.com reader for years, their articles and testing methods are (super) great, but like others review site they haven't metion about bad caps plague.. except the xbitlabs.com iirc...

Quote:

I've already bought Sanyo MV-WX replacement caps (not same physical size though) will report back when I have swapped those caps...

Recapped the PSU today with said Sanyo MV-WX caps, PSU works fine now. No problem to start the computer when it's cold...

It was a tight fit with the cap behind the cable harness though, I had to place the cap about 10mm above the PCB, also the big cap at the very side of the board, 3300uF had to be tilted slightly to not touch the PSU's casing...

Just came home from the MotoGP in Sachenring Germany, 21:st place for my Rider Andreas in 250cc ;-)

Though when I started my comp same problem as before... When I made the order I forgot that one cap was 1000uF and 10v, so I got a 6,3v and hence swapped that one with a used one from a Epox 8KHA mobo (all caps on that mobo look ok)

Well, of course that cap had spewed electrolyte all over it... So I took a multimeter and checked, 5,20v so I swapped it with a Sanyo MV-WX 1000uF 6,3v cap and now the PSU works fine again, gotta love these cap problems ;-) (the failed cap was a GSC 1200uF 10V 105°C "T10A" cap with no date on it....

Just as a follow up the PSU exploded a few weeks ago, I'm sure it was not due to my caps though... But man, the bang was so loud I lifted a meter of my chair!

I have a windowed case and actually saw sparks and flames come out of the underside of the PSU!

Upon inspection two resisitors where completley blown away, the only thing left was two solder pads on the circuit board and allot of black blow resistor stuff on the close by transformers ;-)

The thing that amazed me was that the smaller heatsink of the two was over 100°C hot, I could feel the heat so I wet my finger and touched it brefily and there was the nice cooking sound ;-) Put my tempsensor on and it showed 90, 95, 99 and then HHH ;-)

Mind you this was after I had managed to take the PSU out of the computer and cover off it which took around 5-10 minutes...

Gotta love them computer parts! Fortunantley nothing bar the PSU got damaged and my computer is up and running totally stable again... Funny thing to note is that it was very stable right up to this explosion of my PSU...

bet the mosfets on the primary side caused the flameout.seen many cheap psu where they run too hot and die like that.with near 400v and some big filter caps behind it when the choppers go the cases sometimes explode leaving only the metal mounting tab.

kc8, I noticed when I looked at the pic last night that the apparent source-point of the frying was right by the corner of the switch device heatsink. OTOH, it looks like the MOSFET or transistor at that end of the heatsink is intact. I was wondering whether an MOV fried due to one of the I/P lytics shorting, but that should blow the fuse. My best guess from the pic is that a MOSFET/transistor failed, causing either a snubber resistor or a gate drive (base drive) resistor to blow up. Electronic "autopsies" can be an interesting mental exercise.

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Just out of pure curiosity I desoldered the two main caps and saw that the two transistors connected to the heatsink where also burned...
A look on the underside of the PCB revealed that their "collector" pin was not soldered to the PCB anymore, probably the root cause of the problem...

A look right above this point also revels what was seen in the first pic I posted; the solder joint for R10 has actually melted!

The reason I bought the Seasonic PSU was actually because they manufacture their PCB's themselves, so in other words they are hopefully better built for silent (read:hot) operation... And according to Tom's Hardware review of them they have the least ripple and most stable voltage regulation of most PSU's. On top of that they are listed high on Silent PC Reviews recommended silent PSU's list...

And the few weeks I've had the thing it has worked great, it's very silent... I used a crap "350w PSU that weights 200gram" before I got my Seasonic PSU delivered and then my computer crashed about 4 times per day! Since I got the Seasonic PSU my computer has not crashed once!

The switch devices are transistors, a variant of a TO-220-package series created by Motorola in the late 70s. It's very likely that the device got so hot that solder at the center lead reflowed and dripped out; the same might have happed with the resistor. Looks like the resistor was the source of the smoke and flames, probably a base drive resistor. I'll bet your PWM chip is zorched.